Example
import gfx.math.approx : approxUlp;
auto v1 = DVec3(12, 4, 3);
auto v2 = DVec3(-5, 3, 7);
assert(approxUlp(dot(v1, v2), -27));
auto v = DVec3(3, 4, 5);
assert(approxUlp(squaredMag(v), 50));
assert(approxUlp(normalize(FVec3(4, 0, 0)), FVec3(1, 0, 0)));